| Date | Sat, 15 Aug 2015 11:15:23 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFCv5 PATCH 34/46] sched: Enable idle balance to pull single task towards cpu with higher capacity |
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On Tue, Jul 07, 2015 at 07:24:17PM +0100, Morten Rasmussen wrote: > +++ b/kernel/sched/fair.c > @@ -7569,6 +7569,13 @@ static int need_active_balance(struct lb_env *env) > return 1; > } > > + if ((capacity_of(env->src_cpu) < capacity_of(env->dst_cpu)) && > + env->src_rq->cfs.h_nr_running == 1 && > + cpu_overutilized(env->src_cpu) && > + !cpu_overutilized(env->dst_cpu)) { > + return 1; > + } > + > return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); > }
Doesn't this allow for a nice game of ping-pong? Where if a task runs on CPU X and generates interrupts there, its capacity will lower and we'll migrate it over to CPU Y because that isn't receiving interrupts.
Now the task is running on Y, will generate interrupts there, and sees X as a more attractive destination.
goto 1
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